getrusage • man page

getrusage - get resource usage

getrusage • man page

getrusage - get resource usage

getrusage (2)

Leading comments

Copyright (c) 1992 Drew Eckhardt, March 28, 1992
and Copyright (c) 2002 Michael Kerrisk
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Permission is granted to make and distribute verbatim copies of this
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Permission is granted to copy and distribute modified versions of this
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(The comments found at the beginning of the groff file "man2/getrusage.2".)

NAME

SYNOPSIS

DESCRIPTION

getrusage()
returns resource usage measures for
who,
which can be one of the following:

RUSAGE_SELF

Return resource usage statistics for the calling process,
which is the sum of resources used by all threads in the process.

RUSAGE_CHILDREN

Return resource usage statistics for all children of the
calling process that have terminated and been waited for.
These statistics will include the resources used by grandchildren,
and further removed descendants,
if all of the intervening descendants waited on their terminated children.

RUSAGE_THREAD (since Linux 2.6.26)

Return resource usage statistics for the calling thread.
The
_GNU_SOURCE
feature test macro must be defined (before including
any
header file)
in order to obtain the definition of this constant from
<sys/resource.h>.

The resource usages are returned in the structure pointed to by
usage,
which has the following form:

Not all fields are completed;
unmaintained fields are set to zero by the kernel.
(The unmaintained fields are provided for compatibility with other systems,
and because they may one day be supported on Linux.)
The fields are interpreted as follows:

ru_utime

This is the total amount of time spent executing in user mode,
expressed in a
timeval
structure (seconds plus microseconds).

ru_stime

This is the total amount of time spent executing in kernel mode,
expressed in a
timeval
structure (seconds plus microseconds).

ru_maxrss (since Linux 2.6.32)

This is the maximum resident set size used (in kilobytes).
For
RUSAGE_CHILDREN,
this is the resident set size of the largest child, not the maximum
resident set size of the process tree.

ru_ixrss (unmaintained)

This field is currently unused on Linux.

ru_idrss (unmaintained)

This field is currently unused on Linux.

ru_isrss (unmaintained)

This field is currently unused on Linux.

ru_minflt

The number of page faults serviced without any I/O activity; here
I/O activity is avoided by "reclaiming" a page frame from
the list of pages awaiting reallocation.

ru_majflt

The number of page faults serviced that required I/O activity.

ru_nswap (unmaintained)

This field is currently unused on Linux.

ru_inblock (since Linux 2.6.22)

The number of times the filesystem had to perform input.

ru_oublock (since Linux 2.6.22)

The number of times the filesystem had to perform output.

ru_msgsnd (unmaintained)

This field is currently unused on Linux.

ru_msgrcv (unmaintained)

This field is currently unused on Linux.

ru_nsignals (unmaintained)

This field is currently unused on Linux.

ru_nvcsw (since Linux 2.6)

The number of times a context switch resulted due to a process
voluntarily giving up the processor before its time slice was
completed (usually to await availability of a resource).

ru_nivcsw (since Linux 2.6)

The number of times a context switch resulted due to a higher
priority process becoming runnable or because the current process
exceeded its time slice.

RETURN VALUE

On success, zero is returned.
On error, -1 is returned, and
errno
is set appropriately.

ERRORS

EFAULT

usage
points outside the accessible address space.

EINVAL

who
is invalid.

ATTRIBUTES

For an explanation of the terms used in this section, see
attributes(7).

NOTES

Including
<sys/time.h>
is not required these days, but increases portability.
(Indeed,
struct timeval
is defined in
<sys/time.h>.)

In Linux kernel versions before 2.6.9, if the disposition of
SIGCHLD
is set to
SIG_IGN
then the resource usages of child processes
are automatically included in the value returned by
RUSAGE_CHILDREN,
although POSIX.1-2001 explicitly prohibits this.
This nonconformance is rectified in Linux 2.6.9 and later.

The structure definition shown at the start of this page
was taken from 4.3BSD Reno.

Ancient systems provided a
vtimes()
function with a similar purpose to
getrusage().
For backward compatibility, glibc also provides
vtimes().
All new applications should be written using
getrusage().

SEE ALSO

COLOPHON

This page is part of release 4.13 of the Linux
man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
www.kernel.org/doc/man-pages